Hinged conducting means for disconnecting switch



Jan. 30, 1968 c. w. UPTON, JR 3,366,753

HINGED CONDUCTING MEANS FOR DISCONNECTING SWITCH Filed Oct. 21, 1966 2Sheets-Sheet 1 48 29 g O O A433 44 6i lfieg, v37

IO FIGE.

WITNESSES INVENTORS 7 140M Chester W. Upfonm.

/ W Maw ATTORNEY Jan. 30, 1968 c. w. u'PToN, JR 3,366,753

HINGED CONDUCTING MEANS FOR DISCONNECTING SWITCH Filed Oct. 21, 1966 "2Sheets-Sheet 2 United States Patent 3,366,753 HINGE!) CONDUCTDIG MEANSFOR DISCONNECTING SWITCH Chester W. Upton, Jr., Tralford, Pa., assignorto Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation ofPennsylvania Filed Oct. 21, 1966, Ser. No. 588,530 4 Claims. (Cl.200-48) ABSTRACT OF THE DISCLOSURE A high voltage disconnect switch inwhich the hinge member pivotally supporting the switch blade has acentral tubular portion inside of which a generally C-shaped, resilientconducting member is disposed; the C-shaped member being between andengaging both a portion of the connecting link and the hinge member tomaintain a conducting path between the switch frame and the blade whenthe blade is disengaged from the stationary contacts.

This invention relates to disconnecting switches and more particularlyto hinged conducting structures which form part of such switches.

In the construction of certain known types of disconnecting switches,such as disclosed in US. Patent 2,527,- 924, issued Oct. 31, 1950, toFjellstedt et al., a movable switch blade is actuated to engage anddisengage a pair of associated spaced main stationary contacts or breakjaws at the opposite ends of the switch blade during the clos ing andopening of the switch. Since such switches are frequently required tointerrupt different magnitudes f charging or magnetizing currents duringthe opening of the switch, which may involve the use of arcing horns atthe free end of the switch blade to protect the main contacts and thecontact area on the switch blade, it has been found necessary to providea bridging conducting member at the hinged end of the switch blade inorder to maintain an electrically conducting path from the switch bladeto the supporting hinge structure to thereby prevent arcing and burningor pitting of the main stationary contacts of the switch at the hingedend of the switch blade when the hinged end of the switch blade isdisengaged from the latter contacts during the opening of the switch.One type of bridging conducting member which has been employed for thispurpose comprises a conducting leaf spring which extends from astationary support at the hinged end of the switch blade to bear againstthe external surfaces of the switch parts which are secured to thehinged end of the switch blade. It has been found that this type ofbridging conducting arrangement is subject to operating problems ormalfunctions particularly in icy weather conditions or in corrosiveatmospheric conditions since the contact pressure provided by the leafspring may be reduced or inadequate to clean the associated contactsurfaces and to maintain an adequate conducting path during long periodsof exposure to such atmospheric conditions. It is therefore desirable toprovide an improved disconnecting switch structure of the type describedincluding improved hinged conducting means.

It is an object of this invention to provide a new and improveddisconnecting switch structure.

Another object of this invention is to provide an improved hingedconducting means for disconnecting switches.

A more specific object of this invention is to provide Other objects ofthe invention will, in part, be Obvious and will, in part, appearhereinafter.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description, taken inconjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a disconnecting switch structureembodying the principal features of the invention;

FIG. 2 is a top plan view of the disconnecting switch shown in FIG. 1;

FIG. 3 is a view, partly in side elevation and partly in section, of aportion of the disconnecting switch shown in FIG. 1;

FIG. 4 is a view, partly in end elevation and partly in section, takenalong the line IV-IV in FIG. 3;

FIG. 5 is a view, in side elevation, of a portion of the disconnectingswitch shown in FIG. 1 and illustrating the position of certain partsduring the opening movement of the switch blade which forms part of theswitch; and

FIG. 6 is a sectional view of a portion of the structure shown in FIG.3, taken along the line VIVI in FIG; 3.

Referring now to the drawings and FIGS. 1 and 2 in particular, there isshown a disconnecting switch assembly 10 which comprises three spacedinsulator stacks 32, 34 and 36 mounted upon a common base support 44.The base 44 is preferably a metal channel having flanges which extendoutwardly from the sides of the channel. Each of the insulator stacks32, 34 and 36 comprises a plurality of insulators which are preferablyformed from porcelain or a similar material. The number of insulatorsrequired in each of the insulator stacks 32, 34 and 36 depends upon thevoltage of the system in which the disconnecting switch 10 is applied.The insulator stacks 32 and 34 are mounted upon the fixed pedestals orspacers 33 and 37, respectively, which may be secured to the top of thebase 44. The insulator stack 34 is mounted upon a shaft 61, the lowerend of which is rotatably mounted in a bearing 63 which is secured tothe base 44. An operating lever or crank arm 62 may be secured to theshaft 61 to rotate the insulator stack 34 during the operation of thedisconnecting switch 10, as will be explained hereinafter.

The disconnecting switch 10 includes a first generally U-shaped mainstationary contact assembly or break jaw assembly 2%) which is mountedon and secured to the top of the insulator stack 32, as shown in FIGS. 1and 2. The stationary contact assembly 20 includes a pair of spacedcontact jaws 48 which are interconnected by a base portion or bightportion that is secured to the top of the insulator stack 32 by suitablemeans, such as bolts. A terminal pad 46 which is adapted to receive aterminal connector is also secured to the top of the insulator stack 32and includes a vertical extension 46A which may be formed integrallytherewith and which acts as a stop for the movement of the associatedswitch blade 42 into engagement with the contact jaws 48. In addition, astationary arcing horn 49 may also be secured to the top of theinsulator stack 32 as shown in FIGS. 1 and 2.

The contact jaws 48 are of the reverse loop type which have thecharacteristic of magnetically forcing the associated switch blade 42downwardly between the break jaws in a direction toward the base portionwhich interconnects the contact jaws and against the blade stop 46A whena relatively high momentary current flows through the disconnectingswitch 10. The contact jaws 48 are preferably formed from a suitablematerial which combines relatively high electrical conductivity withexcellent spring characteristics, such as zirconium copper or cadmiumchrome copper. The resilient nature of the contact jaws 48 substantiallyeliminates the need for additional spring or biasing means to bias thecontact 3 jaws 48 toward one another for gripping the free end of theassociated switch blade 42 when the switch blade 42 is actuated toengage the contact jaws 48.

The disconnecting switch also includes a second main stationary contactassembly 30 which is mounted on a generally U-shaped stationary supportframe 80 which in turn is mounted on top of and secured to the insulatorstack 36 and is formed or cast from a suitable material which combinesrelatively high electrical conductivity with suflicient structuralstrength, such as an aluminum bronze alloy. The support frame 81), asillus trated, includes a terminal pad 86 which may be formed integrallytherewith and which is adapted to receive a terminal connector. Thesecond main stationary contact assembly or main hinge contact assembly30 includes a pair of spaced contact jaws 92 which are interconnected bya base portion or bight portion which is secured to a central shoulderor bracket portion of the support frame 30, as indicated at 83, bysuitable means, such as bolts. Similarly to the contact jaws 48, thecontact jaws 92 are preferably formed from a suitable material whichcombines relatively high electrical conductivity with excellent springor resilient characteristics, such as the materials previouslymentioned, to eliminate the need for additional spring means or biasingmeans to bias the contact jaws 92 toward one another to providesufiicient contact pressure with the adjacent end of the associatedswitch blade 42 when the switch blade 42 engages the contact jaws 92.

In order to electrically bridge the spaced main stationary contactassemblies and 30 just described when the disconnecting switch 10 is inthe closed position shown in FIGS. 1 and 2, the movable switch blade 42is disposed to engage both of the stationary contact assemblies 20 and30 along an axis which extends between the contact assemblies 20 and 30when the switch 10 is in the closed circuit condition shown in FIGS. 1and 2. As illustrated, the switch blade 4-2 is generally tubular inconfiguration with the opposite ends being generally rectangular incross-section to provide high pressure contact areas which engage theassociated contact jaws 48 and 92 of the contact assemblies 20 and 30,respectively. In order to facilitate the interruption of magnetizing orcharging currents during the opening of the switch 10, a movable arcinghorn 47 may be mounted at the free end of the blade 42 to cooperate withthe stationary arcing horn 49 during such an opening operation.

In order to support the switch blade 42 for rotation about its own axisand for arcuate movement about an axis which extends generallytransversely with respect to the axis of the switch blade 42, the spacedarms 82 of the support frame 80 are disposed on opposite sides of theright end of the switch blade 42, as viewed in FIGS. 1 and 2. The hingemember 72 is pivotally supported between the arms 82 of the supportframe 80 by the bolts 84 which pass through aligned openings in the arms82 and the hinge member 72, as best shown in FIG. 2, with the right endof the switch blade 42 being disposed to pass through the centraltubular por-' tion of the hinge member 72 to engage the associatedcontact assembly 30 when the disconnecting switch 10 is in the closedposition shown in FIGS. 1 and 2. It is to be noted that the hinge member72 is rotatable about an axis which extends through the bolts 84, asviewed in FIG. 2, and which intersects the axis of the switch blade 42at substantially a right angle.

In order to actuate the switch blade 42 between open and closedpositions with respect to the associated contact assemblies 20 and 30,the connecting link member 90 is secured to the switch blade 42 formovement therewith. In particular, the connecting link 90 includes afirst portion 138 which is secured to the switch blade 42 by suitablemeans, such as the bolt 85, which passes through aligned openings in thefirst portion 138 of the connecting link 90 and the switch blade 42. Thefirst portion 138 of the connecting link which is generally tubular inconfiguration includes a portion indicated at 138A which isconcentrically disposed between the hinge member 72 and the switch blade42 and which projects axially along the switch blade 42 to the right ofthe hinge member 72, as viewed in FIG. 3. In order to rotatably supportthe switch blade 42, along with the first portion 138 of the connectinglink 90, in the central portion of the hinge member 72, the flangedsleeve bearing members 142 and 144 are disposed between the firstportion 138 of the connecting link 90 and the hinge member 72 as bestshown in FIG. 3. The flanged s eeve bearing members 142 and 144 areaxially spaced from one another along the switch blade 42 and are formedfrom a suitable material, such as bronze, which is coated with amaterial having a relatively low coefficient of friction, such as thematerial polytetrafluoroethylene which is sold under the trademarkTeflon. The bearing members 142 and 144 are maintained in assembledrelationship with the associated hinge member 72 and the connecting link90 by the flange portion 136 which is provided on the first portion 138of the connecting link 96 and the retaining ring 152, which is disposedin a groove provided adjacent to the end of the portion 138A of theconnecting link 90 on the other side of the hinge member. The connectinglink 90 is also provided with an arm portion 132 which is tubular inconfiguration and which projects from the first portion 138 of theconnecting link 90 at an ange of substantially 45 degrees with respectto the longitudinal axis of the switch blade 42. The axis of the armportion 132 of the connecting link 90 also intersects the axis ofrotation of the switch blade 42 which extends between the bolts 84 aspreviously described.

In order to actuate the arm portion 132 of the connecting link 90 and,in turn, the switch blade 42, the crank member 52 is mounted on top ofand secured to the insulator stack 34 by suitable means, such as bolts.The crank member 52 includes a base portion 52A and a bearing portion52B which is adapted to receive the arm portion 132 of the connectinglink 90. In order to rotatably support the connecting link 90 in thebearing portion 52B of the crank member 52, a pair of flanged sleevebearing members 122 and 124 are disposed at the opposite ends of thebearing portion 523 of the crank member 52 between the arm portion 132of the connecting link 90 and the inner surface of the bearing portion52B of the crank member 52. In order to maintain the bearing members 122and 124 in assembled relationship with the associated arm portion 132 ofthe connecting link 90 and the bearing portion 52B of the crank member52, the flange portion 134 is provided on the connecting link 9% and aretaining ring 126 is disposed on the lower end of the arm portion 132of the connecting link 94 in a groove provided adjacent to the lower endof the arm portion 132. It is to be noted that the crank member 52 isrotatable with the insulator stack 34 about an axis which substantiallyintersects the longitudinal axis of the switch blade 42, the axis ofrotation of the hinge member 72, and the axis of rotation of the armportion 132 of the connecting link 91), which intersects thelongitudinal axis of the switch blade 42 at an angle of substantially 45degrees and which also intersects the axis of rotation of the crankmember 52 at an angle of substantially 45 degrees, as best shown in FIG.3.

In order to limit the arcuate travel or movement of the switch blade 42from the closed position shown in FIG. 1 to the open position which isangularly displaced from the closed position shown in FIG. 1 by an angleof substantially 90 degrees about the axis of rotation of the hingemember 72, the stop member 53 is mounted on the base portion 52A of thecrank member 52 and may be formed integrally therewith to engage thelower end of the switch blade 42, as best shown in FIG. 5, when theswitch blade 42 is actuated to the open position.

In order to assist the actuation of the switch blade 42 from the openposition which is angularly displaced from the closed position shown inFIG. 1 by substantially 90 degrees as just mentioned, when themechanical advantage of the hinge conducting structure just described issubstantially at a minimum, the cam member or projecting portion 52C, asshown in FIG. 6, is mounted on or formed integrally with the bearingportion 52B of the crank member 52 and is disposed to engage one end ofan arm 72A which extends from a flange portion 723 on the hinge member72 toward the contact assembly 30 and the contact jaws 92, as shown inFIG. 3. More specifically, when the switch is actuated from the openposition, in which the blade 42 is disposed generally vertical- 1y, asviewed in FIG. 5, the cam portion 52C on the crank member 52 engages thearm 72A on the hinge member 72 from about 10 to of the rotation of theinsulator stack 34 during the initial rotation of the insulator stack 34toward the closed position to transmit a driving torque to the switchblade 42 directly from the crank member 52 to the hinge member 72 andthe switch blade 42.

In order to maintain a conducting path between the switch blade 42 andthe conducting frame support 80 during the opening movement of theswitch blade 42, a generally C-shaped conducting member 112 is disposedgenerally concentrically between the hinge member 72 and the firstportion 138A of the connecting link 99, as best shown in FIGS. 3 and 4,to engage both the inner surface of the central portion of the hingemember 72 and the outer surface of the portion 138A of the connectinglink 90 at a plurality of points, as shown in FIG. 4, to prevent anyburning or arcing at the hinged conducting structure of thedisconnecting switch 10 previously described. The conducting member 112is preferably formed from a material which combines relatively highelectrical conductivity with excellent spring or resilientcharacteristics such as phosphorus bronze or a zirconium copper alloy.Because of the resilient or spring characteristic of the material fromwhich the conducting member 112 is formed, different points or portionsof the conducting member 112 are biased into engagement with both thehinge member 72 and the connecting link 90 and more specifically bearsagainst the central portion of the hinge member 72 and the outer surfaceof the first portion 138A of the connecting link 90. It is to be notedthat the conducting member 112 is disposed axially between the bearingmembers 142 and 144, as best shown in FIG. 3. It is also important tonote that the conducting member 112 is disposed internally inside thehinge member 72 and is protected by the bearing members 142 and 144 aswell as by the first portion 138A of the connecting link 90 to preventthe formation of ice or the adverse effect of corrosive atmosphereswhich might otherwise affect the performance of the conducting member112 or the conducting path which is provided by the conducting member112 during long service of the disconnecting switch 10.

In the overall operation of the disconnecting switch 10, when theinsulator stack 34 is rotated by an external operating mechanism (notshown) through the crank member or operating lever 62, from the positionshown in FIGS. 1 and 2, the switch blade 42 is first actuated throughthe crank member 52, and the connecting link 90, as guided by the hingemember 72, to rotate about its own longitudinal axis until the contactpressure between the contact surfaces provided at the free end of theswitch blade 42 as indicated at 42A is reduced. Simultaneously orsubsequently, the switch blade 42 is rotated in an arcuate path aboutthe axis which extends through the bolts 84 from the closed positionindicated in FIGS. 1 and 2 to the open position which is displaced fromthe closed position by an angle of substantially 90 degrees in aclockwise direction, as viewed in FIG. 1. During the opening movement ofthe switch blade from the closed position shown in FIG. 1, both ends ofthe switch blade will be disengaged from the associated contact assem- 6blies 20 and 3t and after the right end of the switch blade 42 as viewedin FIGS. 1 and 2 is disengaged from the contact assembly 30, theconducting member 112 maintains an electrically conducting path from theswitch blade 42 to the electrically conducting support which extendsfrom the switch blade 42, through the connecting link 90, which is alsoformed from an electrically conduc ing material, the conducting member112, the electrically conducting hinge member 72, the electricallyconducting bolts 84 and the contact areas provided on the arm portions192 of the hinge member 72, which are generally circular inconfiguration, as best shown in FIGS. 2 and 3. The latter conductingpath is very important in preventing arcing or pitting or burning of thehinge conducting structure provided as part of the disconnecting switch10 when the disconnecting switch 10 is required to interrupt charging ormagnetizing currents in a particular application which would otherwisecause such arcing or pitting in a disconnecting switch contact. Aspreviously mentioned, the stop member 53 provided on the base portion52A of the crank member 52 limits the arcuate travel of the switch blade42 from the closed position shown in FIGS. 1 and 2 to the open positionwhich is angularly displaced from the closed position by an angle ofsubstantially degrees, as best shown in FIG. 5 where the switch blade 42is shown approaching its ultimate open position.

In the closing operation of the disconnecting switch 10, the insulatorstack 34 is rotated through the crank member or operating lever 62 fromthe position indicated in phantorn at 62 in FIG. 2 to the positionindicated in solid in FIG. 2 to thereby actuate the switch blade 42 fromthe open position through the crank member 52 and the connecting link90, as guided by the hinge member 72, to the closed position shown inFIGS. 1 and 2. As previously mentioned, during the initial rotation ofthe insulator stack 34 from the position which corresponds to theposition of the operating lever indicated at 62 in FIG. 2, the arm 72Aprovided on the hinge member 72 is engaged by the cam surface 52C on thebearing portion 52B of the crank member 52, as .best shown in FIG. 6, toactuate the switch blade 42 initially from the open position when themechanical advantage of the drive system which includes the insulatorstack 34 and the crank member 52 as well as the connecting link 90 andthe hinge member 72 is substantially at a minimum to insure properoperation of the disconnecting switch 10 during closing of thedisconnecting switch. It has been found that the driving torque orforces exerted on a switch blade 42 through the cam member 52C and thearm 72A of the hinge member 72 are effective during a closing operationof the switch blade 42 from about 10 degrees to 20 degrees of theinitial rotation of the insulator stack 34 from the position whichcorresponds to the position of the operating lever, as indicated at 62in FIG. 2, toward the position of the insulator stack 34 whichcorresponds to the position of the operating lever 62 as shown in solidlines in FIG. 2. It is to be noted that during the final movement of theswitch blade 42 to the closed position shown in FIG. 1, the blade 42 isrotated about its own axis to insure adequate contact pressure betweenthe contact surfaces at each end of the blade and the associated contactjaws 48 and 92.

It is to be understood that in certain applications the disconnectingswitch structure shown may be modified to provide a conducting pathdirectly between the switch blade 42 and the electrically conductinghinge member 72 by enlarging the outer diameter of the switch blade 42as best indicated in FIG. 3 and omitting theportion of the connectinglink Q0, as indicated at 138A, which extends from the flange portion 136to the retaining ring 152 with the bearing members 142 and 144 beingthen disposed between the inner surface of the central portion of thehinge member 72 and the outer surface of the'enlarged switch blade 42 asthus modified. In such a modified arrangement, the bearing members 142and 144 may be main- 7 tained in assembled relationship with theassociated hinge member 72 and the switch blade 42, as thus modified, bythe flange portion 135 of the modified connecting link 98 and aretaining ring similar to the retaining ring 152 which would be disposedin a suitable groove provided in the enlarged portion of the switchblade 42 as modified.

It is important to note that the conducting path maintained by theconducting member 112 in a construction as disclosed is only effectiveor required during the portion of the arcuate travel of the switch blade42 in an opening operation after the opposite ends of the switch blade42 which provide the high pressure contact areas have both beendisengaged from the associated main stationary contact assemblies and30, respectively, to prevent the arcing or pitting or burning of thehinged conducting structure of the disconnecting switch 19 that wouldotherwise result and that the conductive path provided by the connectingmember 112 is therefore only required to conduct substantial currentduring a portion of the opening travel of the switch blade 42. Thenormal current path through the disconnecting switch 10 when the switchblade 42 is in the closed position shown in FIGS. 1 and 2 extends fromthe terminal pad at the left end of the switch 10, through the contactjaws 48, the contact portion 42A of the switch blade 42, the main bodyof the switch blade 42, the contact jaws 92 of the stationary contactassembly 30 to the electrically conducting frame support Stl and finallyto the terminal pad as at the right end of the disconnecting switch 10as viewed in FIGS. 1 and 2. The normal conducting path through theswitch it) is designed to have a relatively lower resistance than theconducting path which includes the conducting member 112.

The apparatus embodying the teachings of this invention has severaladvantages. For example, in a disconnecting switch of the type describedin which the opposite ends of the switch blade are actuated to bedisengaged from both of the main stationary contact assemblies asdescribed, a conducting path is maintained from the switch blade throughthe associated hinged conducting structure previously described by theconducting member 112 and the associated conducting parts which preventsarcing or burning or pitting of the different parts which make up thehinged conducting structure of the switch 10. The conducting path whichis maintained during a portion of the opening travel of the switch bladein a switch structure as described is completely protected from adverseweather conditions, such as ice and snow and from corrosive atmosphericconditions, which might otherwise reduce the contact pressures or theresilience of the conducting mernber 112 during long periods of serviceof the disconnecting switch 10.

Since numerous changes may be made in the above described apparatus anddifferent embodiments of the invention may be made without departingfrom the spirit and scope thereof, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. A disconnecting switch comprising a pair of stationary contactmembers disposed in spaced relation along a first axis, a switch bladedisposed generally along the first axis to engage both of the stationarycontact memmers when the switch is in the closed position, a conductingstationary frame disposed adjacent to one end of the blade and havingone of the stationary contact members mounted thereon, a conductinghinge member having a central tubular portion pivotally supported on theframe for rotation about a second axis which intersects the first axisat substantially a right angle, said one end of the blade being disposedto pass through and being radially spaced from the central tubularportion of the hinge member, a connecting link secured to the bladeadjacent to said one end and having a first portion rotatably supportedbetween the blade and the hinge member and an arm projecting at an angleof substantially 45 with respect to the first axis, a crank memberrotatable about a third axis which substantially intersects said firstand second axes and having a bearing portion adapted to rotatablyreceive the arm of the connecting link, and a generally C-shaped,resilient conducting member disposed inside the central tubular portionof said hinge member between and engaging both the first portion of theconnecting link and the hinge member to maintain a conducting pathbetween the frame and the blade which extends through the generallyC-shaped conducting member and the first portion of the connecting linkwhen the crank member is rotated to actuate the blade to a disengagedposition with respect to both of the stationary contact members.

2. The combination as claimed in claim 1 wherein a pair of flangedsleeve bearing members are rotatably dis posed between the hinge memberand the first portion of the connecting link on the opposite sides ofthe generally C-shaped conducting member.

3. The combination as claimed in claim 1 wherein both of the stationarycontact members are generally U-shaped in configuration with theopposite ends of the blades which engage the stationary contact membersbeing generally rectangular in cross-section.

4. A disconnecting switch comprising a pair of stationary contactmembers disposed in spaced relation along a first axis, a switch bladedisposed generally along the first axis to engage both of the stationarycontact members when the switch is in the closed position, a conductingstationary frame disposed adjacent to one end of the blade and havingone of the stationary contact members mounted thereon, a conductinghinge member having a central tubular portion pivotally supported on theframe for rotation about a second axis which is generally transverse tothe first axis, said one end of the blade being disposed to pass throughand being radially spaced from the tubular portion of the hinge member,a connecting link having a first portion secured to said blade adjacentto said one end for movement with the blade and an arm projecting at anangle of substantially 45 with respect to the first axis, a crank memberrotatable about a third axis which substantially intersects said firstand second axes and having a bearing portion adapted to rotatablyreceive the arm of the connecting link, and a generally C-shaped,resilient conducting member disposed inside the central tubular portionof said hinge member between and directly engaging both the hinge memberand the blade to maintain a conducting path between the frame and theblade which extends through the last-mentioned conducting member and thehinge member when the crank member is rotated to actuate the blade to adisengaged position with respect to both of the stationary contactmembers.

References Cited UNITED STATES PATENTS 2,830,144 4/1958 Fjellstedt200--48 3,240,887 3/1966 Melbye 200-48 3,243,561 3/1966 Foti 200-48ROBERT K. SCI-IAEFER, Primary Examiner.

H. HOHAUSER, Assistant Examiner,

